Summary:
A robust, console-based educational tool designed to manage and execute multiple-choice examinations. The system emphasizes modular design, separating the question logic from the engine's execution flow.
Learning Objectives:
Encapsulation: Managing question data and validation through private members and public interfaces.
Object Composition: Utilizing a std::vector of Class Objects to build a dynamic database.
Input Validation: Implementing "fail-safe" console handling to prevent infinite loops during data entry.
The Source Code
This main.cpp is optimized for Code::Blocks using the MinGW toolchain. It includes <limits> for buffer clearing and <iomanip> for score formatting.
#include <iostream>
#include <vector>
#include <string>
#include <limits>
#include <iomanip>
using namespace std;
// Class representing a single Multiple Choice Question
class Question {
private:
string text;
string options[4];
int correctAnswer; // Index 1-4
public:
Question(string q, string opts[4], int ans) {
text = q;
for(int i = 0; i < 4; i++) options[i] = opts[i];
correctAnswer = ans;
}
void display(int qNum) const {
cout << "\nQuestion " << qNum << ": " << text << endl;
for(int i = 0; i < 4; i++) {
cout << " " << (i + 1) << ". " << options[i] << endl;
}
}
bool checkAnswer(int userChoice) const {
return userChoice == correctAnswer;
}
int getCorrectAnswer() const { return correctAnswer; }
};
class QuizEngine {
private:
vector<Question> bank;
int score;
public:
QuizEngine() : score(0) {}
void addQuestion(const Question& q) {
bank.push_back(q);
}
void run() {
cout << "========================================" << endl;
cout << " WELCOME TO THE ACADEMIC QUIZ GAME " << endl;
cout << "========================================" << endl;
for(size_t i = 0; i < bank.size(); i++) {
bank[i].display(i + 1);
int choice = getValidInput();
if(bank[i].checkAnswer(choice)) {
cout << ">> Correct!" << endl;
score++;
} else {
cout << ">> Wrong. The correct answer was " << bank[i].getCorrectAnswer() << "." << endl;
}
}
displayResults();
}
private:
int getValidInput() {
int input;
while (true) {
cout << "Your Answer (1-4): ";
if (cin >> input && input >= 1 && input <= 4) {
return input;
} else {
cout << "[Error] Invalid input. Please enter a number between 1 and 4." << endl;
cin.clear(); // Clear error flags
cin.ignore(numeric_limits<streamsize>::max(), '\n'); // Discard buffer
}
}
}
void displayResults() {
double percentage = (static_cast<double>(score) / bank.size()) * 100;
cout << "\n----------------------------------------" << endl;
cout << "QUIZ FINISHED!" << endl;
cout << "Final Score: " << score << "/" << bank.size() << endl;
cout << "Grade: " << fixed << setprecision(2) << percentage << "%" << endl;
cout << "----------------------------------------" << endl;
}
};
int main() {
QuizEngine myQuiz;
string o1[] = {"C++", "Java", "Python", "Assembly"};
myQuiz.addQuestion(Question("Which language is known for its manual memory management?", o1, 1));
string o2[] = {"Encapsulation", "Polymorphism", "Recursion", "Inheritance"};
myQuiz.addQuestion(Question("Which of these is NOT a primary pillar of OOP?", o2, 3));
string o3[] = {"MinGW", "Visual Studio", "Code::Blocks", "GCC"};
myQuiz.addQuestion(Question("Which of the following is an Integrated Development Environment (IDE)?", o3, 3));
myQuiz.run();
cout << "\nPress Enter to exit...";
cin.ignore();
cin.get();
return 0;
} |
Execution Trace (Sample User Session)
========================================
WELCOME TO THE ACADEMIC QUIZ GAME
========================================
Question 1: Which language is known for its manual memory management?
1. C++
2. Java
3. Python
4. Assembly
Your Answer (1-4): 1
>> Correct!
Question 2: Which of these is NOT a primary pillar of OOP?
1. Encapsulation
2. Polymorphism
3. Recursion
4. Inheritance
Your Answer (1-4): x
[Error] Invalid input. Please enter a number between 1 and 4.
Your Answer (1-4): 3
>> Correct!
Question 3: Which of the following is an Integrated Development Environment (IDE)?
1. MinGW
2. Visual Studio
3. Code::Blocks
4. GCC
Your Answer (1-4): 1
>> Wrong. The correct answer was 3.
----------------------------------------
QUIZ FINISHED!
Final Score: 2/3
Grade: 66.67%
---------------------------------------- |
Academic "Learning Corner"
1. The MinGW "Input Hang" Fix
In standard C++ console applications, if a user enters a character (like 'x') when the code expects an int, std::cin enters a fail state. If you don't clear it, the program will spin in an infinite loop.
cin.clear() resets the internal error state flags.
cin.ignore(numeric_limits<streamsize>::max(), '\n') wipes the "junk" character out of the keyboard buffer so the next cin >> actually waits for new input.
2. Header Justification
<limits>: Essential for numeric_limits, providing a platform-independent way to clear the input buffer.
<iomanip>: Used for setprecision(2). In academic reporting, providing raw doubles (like 66.666667%) is considered unprofessional; fixed-point notation ensures clean UI.
3. Object Composition
The QuizEngine does not inherit from Question. Instead, it "has-a" collection of questions. This is a fundamental OOP design pattern that makes the code more flexible—you can add 10 or 100 questions without changing the Engine's logic.
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...till the next post, bye-bye & take care
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